Fig. 6. Schwann cell BL formation and axon interactions in 2 mutants. (A) Normal Schwann cells form continuous BLs (arrowheads) adjacent to the plasma membrane (PM), with collagen fibrils between cells (Col). (B) In dy^2J, BLs on myelinating cells contained gaps (white arrowheads) and were comparatively indistinct. (C) In dy, myelinating Schwann cell BL is very sparse (black arrowheads) and discontinuous. (D) In nmf417, BLs on myelinating Schwann cells were continuous (arrowheads), but less compact. (E) BLs were absent from premyelinating Schwann cells in nmf417 (arrowheads). AX, axons. (F) In dy^2J, premyelinating Schwann cells also lacked BLs. (G) Premyelinating Schwann cells in dy also lacked BLs (arrowheads). All images show L5 ventral roots. Scale bar: 250 nm (A-D); 500 nm (E-G).